To test whether cognitive ability predicts survival from age 79 to 89 years data were collected from 543 (230 male) participants who entered the study at a mean age of 79.1 years. Most had taken the Moray House Test of general intelligence (MHT) when aged 11 and 79 years from which, in addition to intelligence measures at these two time points,…

The general differentiation hypothesis states that the strength of the correlations among a set of IQ subtests varies with a given variable. Instances of the general differentiation hypothesis that have been considered in the literature include age and ability differentiation. Traditionally, the differentiation effect is attributed to the varying…

This paper compares different theoretical models of the structure of intelligence, based on the analysis of data obtained in a series of measured abilities corresponding to the Spectrum assessment activities (Gardner, Feldman & Krechevsky, 1998) in a sample of 393 children enrolled in kindergarten and first grade. The data were analyzed using…

Item responses to Digit Span and Letter-Number Sequencing were analyzed to develop a better-refined model of the two working memory tasks using the finite mixture (FM) modeling method. Models with ordinal latent traits were found to better account for the independent sources of the variability in the tasks than those with continuous traits, and…

Neuroimaging studies, using various modalities, have evidenced a link between the general intelligence factor (g) and regional brain function and structure in several multimodal association areas. While in the last few years, developments in computational neuroanatomy have made possible the "in vivo" quantification of cortical thickness, the…

The impurity of measures is considered as cause of erroneous interpretations of observed relationships. This paper concentrates on impurity with respect to the relationship between working memory and fluid intelligence. The means for the identification of impurity was the fixed-links model, which enabled the decomposition of variance into…

A previous study on the underlying structure of the Wechsler intelligence test (WISC-R; [Wechsler, D. (1974). Manual WISC-R: Wechsler intelligence scale for children-Revised. New York: Psychological Corporation]), using smallest space analysis (SSA) [Guttman, L., and Levy, S. (1991). Two structural laws for intelligence tests.…

We investigated sex effects and the effects of educational attainment (EA) on the covariance structure of the WAIS-III in a subsample of the Spanish standardization data. We fitted both first order common factor models and second order common factor models. The latter include general intelligence ("g") as a second order common factor.…

Gignac [Gignac, G. E. (2006). "Evaluating subtest "g" saturation levels via the single trait-correlated uniqueness (STCU) SEM approach: Evidence in favor of crystallized subtests as the best indicators of "g"." "Intelligence," 34, 29-46.] used a single-trait correlated uniqueness (STCU) CFA approach to…

Whether results previously found in adults, demonstrating a relationship between intellectual ability, speed of information processing, and memory capacity could be found in young children was studied with 109 children. Findings suggest that children's intelligence cannot be explained using a model of adult intelligence. (SLD)

Raven's matrices and inspection time (IT) were recorded from 56 subjects under five arousal levels. Raven's and IT correlated strongly (r = -0.7) as predicted by processing-speed theories of "g." In line with Eysenck's [Eysenck, H. J. (1967). "The biological basis of personality". Springfield, IL: Thomas] arousal theory of extraversion, there was…

Recent literature suggests a causal link between malnutrition and impaired cognitive development. A selective literature review indicates that the presence or absence of such a link cannot be established. A reanalysis of an experiment indicated after four years of treatment there was no association between cognitive and nutritional status.…

The stability of psychometric "g," the general factor of intelligence, is investigated in simulated correlation matrices and in typical empirical data from a large battery of mental tests. "G" is robust and almost invariant across methods of analysis. A reasonable strategy for estimating "g" is suggested. (SLD)

Adult performance on verbal analogy and classification problems was assessed in terms of outcomes of process execution. Process-outcomes measures accounted for overall performance and were related to ability. Problem forms differed in terms of which measures predicted individual differences. Common process-outcome measures showed highest…

The hierarchical and radex models of ability organization are shown to be parallel. Both suggest a complexity continuum for cognitive performance tasks which, in the radex model, corresponds to the general-to-specific dimension in factor analyses. The bases for this continuum indicate its importance for theories of intelligence. (Author/RD)